Re: [RE-wrenches] Propane Generator, Dual Outback Inverters

[Allan Sindelar]

Mark, Yeah, the gennie is set to come on automatically through the Mate, but the homeowner pays attention. There's about 5kW of array for this off-grid home as well, so it's a gennie-backed PV system. Also, all modules are on trackers (long boring story) so there's plenty of PV in summer, but they depend on the generator as an integral part of charging in the winter, and the owner is involved in system operation. (He happens to be the rare customer with a Ph.D. in physics; so engaged that he successfully added a thermostatically-controlled heat exchanger with fail-safe backup to the generator's coolant lines that he piped into his solar-radiant-with-boiler infloor heating system, to increase generator overall efficiency.) Continuous operation at low load can be harmful and inefficient, but occasional operation isn't something to lose sleep over. Allan Sindelar Allan@positiveenergysolar.com NABCEP Certified Photovoltaic Installer EE98J Journeyman Electrician Positive Energy, Inc. 3201 Calle Marie Santa Fe, New Mexico 87507 505 424-1112 www.positiveenergysolar.com On 7/21/2010 4:25 PM, Mark Frye wrote: Allen,   Can I infer that if you are shutting off the gen before charge rates drop in absorption that you are running only briefly in the absorb phase? Or do your charge currents remain high through out an extended absortion phase?   Perhaps you have plenty of PV which you rely upon to bring the batteries up through the absorption phase, once the gen is shut off.   I would be interest to learn more about your approach to this.   Thanks,   Mark Frye Berkeley Solar Electric Systems 303 Redbud Way Nevada City,  CA 95959 (530) 401-8024 www.berkeleysolar.com    From: re-wrenches-boun...@lists.re-wrenches.org [mailto:re-wrenches-boun...@lists.re-wrenches.org] On Behalf Of Allan Sindelar Sent: Wednesday, July 21, 2010 3:17 PM To: re-wrenches@lists.re-wrenches.org Subject: Re: [RE-wrenches] Propane Generator, Dual Outback Inverters The Onan RS20000 shown in the generators article in HP 131 page 98 has performed flawlessly as backup support to an Outback quad-stack of VFX3648s. Differences, however, are that this 20kW gennie charges four inverters, rather than two; the elevation is 6,600 feet for about a 20% output deration; there are no huge loads above charging draw; and the client is aware enough to shut it off before absorption reduces the charge rate - all different conditions than you have described, as the gennie is usually fully loaded and running in balance. Darryl is right about the amount of words necessary. Allan Sindelar Allan@positiveenergysolar.com NABCEP Certified Photovoltaic Installer EE98J Journeyman Electrician Positive Energy, Inc. 3201 Calle Marie Santa Fe, New Mexico 87507 505 424-1112 www.positiveenergysolar.com

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